Documenting U.S. History: The Civil War through Photography Darlene R. Stille, Heinemann Library, Chicago, Illinois, 2012.
This is not a very good history of the Civil War; but is a better history of photograph and wartime photography. It starts with a god explanation of primary sources versus secondary sources in term of documenting history. Primary sources are letters, diaries or newspaper articles written by witnesses to an event. Official reports such as orders would also be a primary source. A picture also would be a primary source, such as a map drawn to show a path, or a drawing or photographing of a first person witness.
Secondary sources are such things as reports or pictures drawn based on the witness of someone else. This would include biographies or paintings.
Photography had gone through several stages. The first photograph was mad in 1826 by French inventor Joseph Niepce. Fellow Frenchman Louis Daguerre invented the Daguerreotypes which had better image and was us mercury vapor. Tintypes were invented in the 1850s and were easier to use. Glass plates also came into use in the 1850s. The difficulty about photography was the photographer had to take a dark room with him in order to develop the pictures.
Mathew Brady was a famous Civil War photographer. However he more organized teams of photographers because of his failing eyesight. Alexander Gardner and others worked for him and did the actual photography. Because of the limitations of photography, action scenes were not possible. However there are many camps scenes, personal portraits, pictures of officer staff, artillery crews with their cannon. Many after battle pictures were taken. This included photographing dead soldiers. This is the first time this had ever been done. There are also many pictures of the destruction of war; buildings destroyed, mostly in the South. There is documentation through photography of the conditions in prisoner of war camps as well as hospitals.
As I said, a better history of photography rather than the Civil War. I could have used more pictures, but it pointed to a web site which you can search Library of Congress Civil War pictures. They have over 7500 pictures in the public domain.